Recently, there has been an increasing trend toward the use of image sensors based on complementary metal oxide semiconductor (CMOS), rather than charged coupled device (CCD), technology. Advantages of CMOS image sensors include low power usage, compatibility with CMOS logic technology, permitting random access of image data, and circuit integration. In conventional CMOS image sensors, however, increasing circuit complexity may be detrimental to optical performance. As the number of metal interconnect layers increases, so does the distance between the microlenses and photodiodes, reducing light collection efficiency and increasing inter-pixel cross-talk.
Thus, an improved CMOS image sensor is desired.